PT98652B - FILM BAG CONTAINER AND METHOD FOR ITS PRODUCTION - Google Patents

Abstract

Pouches (10) for contg. substances are made from multi-layer film, 2 - 24 weeks old. including at least one barrier layer and at least one sealing layer and having at least a partial transmissivity to aromatic substances and an oxygen transmissivity of at least 600 cm3 per m2 per day per bar. The barrier layer is pref. a polyolefin and the sealing layer is ethylene-vinyl acetate having an average vinyl acetate content of at least 18 wt. The barrier layer is pref. 25 - 100 microns thick and the sealing layer is 50 - 200 microns thick. The film layers are aged 4 - 20 weeks, the exact age depending on the slip agent content of the film. The multilayer film is sealed to form a pouch defining a closed vol., having an upper portion with a spout (15).

Description

Field of the Invention

This invention relates to multi-layer films for the manufacture of bags, which can be sealed using energy with radio frequencies, and in particular bags designed to contain liquids or pastes, showing at least partial transmissibility to oxygen and for aromatic substances.

Background of the Invention

There is a continuous effort to reduce the weight of the mass of material used in the packaging. As part of this effort, substances that have been sold in bottles are now being sold in pouch containers made from film. This reduces the weight of the package to less than half the weight of the bottle. Additional savings may exist if the liquid substance is concentrated prior to packaging in the film. In this way, the amount of packaging film can be further reduced, since diluent is added when using the packaged product. However, a film must have specific properties in order to be efficient when used in packaging. This is the particular case when the packaging film will be formed and / or sealed using radio frequency (RF) energy techniques · In RF sealing techniques, RF energy is used in order to soften the film sufficiently , so that the welding of said film can be carried out. This is an efficient sealing technique, since the two layers of the film that will form the bag are heated until they reach similar temperatures, which can then be welded. When they are sufficiently softened, but before any flow of the film material is carried out, the two layers are welded. This provides significant advantages over techniques that use adhesives or heating the film by conduction, i.e., through contact with a heated plate. In the present case, RF energy also provides more uniform heating and therefore produces good seals.

Although RF energy provides good seals, there are certain requirements regarding the use of RF energy. The film must be able to be heated using RF energy. In other words, it must be able to undergo heating up close to the melting state, through contact with RF energy with a frequency of about 10 MHz (Megahertz) to 50 MHz. This is the most used frequency range for heating polymer materials. Not all polymer films can be heated efficiently to produce good seals using RF energy. The plastic film used in the sealing layer must be bysular ”to be sensitive to RF energy.

The films will also need to have other characteristics, which depend, at least in part, on the substance that will be introduced into the bag made from the film. It has been found that the film, when bleach is introduced into the film pouch, must have a transmissibility to oxygen since the oxygen expands during the storage of bleach bags. If this oxygen cannot be dissipated through the wall of the bag, pressure will be developed inside the bags to the point that ruptures in said bags may occur. If this happens, there will be a loss of product and possibly damage to neighboring areas. In addition, with many substances, it is desirable that some aroma of the substance contained in the bag is transmitted to the outside. This provides the possibility to inform the customer about the aroma of the product. Consequently, it is desirable that the film has partial transmissibility for the aromas.

Brief Summary of the Invention

Particular multi-layer films can be used efficiently in the production of bags through the use of RF energy. The multi-layered film must contain at least one barrier layer and at least one sealing layer. The barrier layer provides the main retention layer, the main layer being resistant. The sealing layer will quickly absorb RF energy, soften and is weldable in the softened state. In a particular assembly, the sealing layer is weldable to itself. The outer layer should also be able to make an impression on it. In addition to providing transport information, the print will act as a sliding agent during the formation of the bag from the film. Additionally, in order to form bags with high strength seals using RF energy, the film should be used to form bags within 2 to 24 weeks and, preferably, within about 4 to 20 weeks after the production of the film.

The preferred film will consist of at least one barrier layer of a polyiefin and at least one sealing layer of ethylene-vinyl acetate. Preferably, ethylene-vinyl acetate layers should have an average vinyl acetate content of at least about 18 weight percent and, even better, at least about 20 weight percent. Therefore, one ethylene-vinyl acetate layer may have a vinyl acetate content of less than 18 or 20 weight percent, while the other layer has a sufficiently high vinyl acetate content, so that the average of both layers is at least about 18 weight percent and preferably 20 weight percent. The film has a thickness of about 125 to 500 microns and, preferably, about 200 to 300 microns. The barrier layer has a thickness of about 25 to 100 microns and, preferably, 40 to 75 microns. The sealing layer is about 50 to 200 microns thick and preferably about 75 to 150 microns thick.

In addition to the above, the film should have an oxygen transmissibility of at least about 600 cm3 / m2 / day / bar and, preferably, at least about 1000 cm3 / m2 / day / bar. The transmissibility of flavorings should be about 1 to 25 percent by weight of the aroma content over a period of 90 days, and preferably about 3 to 15 percent by weight of the aroma content over a period of 90 days. . In this way, the oxygen produced in the partial degradation of a substance, such as bleach, can be removed from the bag and the aroma of the product can be felt by people while the bags remain at the seller.

Brief Description of Drawings

The Figure is a rear view of a pouch container with a spout.

Detailed Description of the Invention

Polymer films are used efficiently in many types of packaging. In many cases, a multi-layered film will have to be used since the film will have particular characteristics, as referred to by the design to be packaged. It should

Sometimes, the characteristic packaging and the substance there is a compatibility. The main substance contained should not normally pass through the polymer film. Seals must be able to be formed

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strong. There are only a few of the features. Additionally, when a bleach is being packaged, the film must have a transmissibility to oxygen. In many cases it is also desirable that some aroma of the product can pass through the film. This allows the consumer to define whether the aroma of a product is acceptable or not.

It has been found that household products, such as bleaches and fabric softeners, can be packaged in film pouches that are made up of at least one barrier layer and at least one sealing layer. Preferably, the barrier layer is a polyolefin such as polyethylene or polypropylene. The polyethylene can be a high or low density polyethylene. The sealing layer is preferably ethylene-vinyl acetate and, even better, ethylene-vinyl acetate in which the average vinyl acetate content is at least about 18 weight percent and preferably at least about 20 percent by weight. Also, in a preferred embodiment, the film should have three layers. These include a layer of polyethylene with a layer of ethylene-vinyl acetate on each side. The polyethylene layer serves as a barrier layer and provides resistance to the film.

The film has a thickness of about 125 to 500 microns and, preferably, about 200 to 300 microns. The polyethylene barrier layer has a thickness of about 25 to 100 microns and, preferably, about 40 to 75 microns. The sealing layers of ethylene-vinyl acetate have a thickness of about 50 to 200 microns and, preferably, 75 to 150 microns. The ethylene-vinyl acetate layers do not need to be the same thickness. However, in many cases, the same thickness will be used.

The film should have an oxygen permeability of at least about 600 cm3 / m2 / day / bar and preferably 1000 cm3 / m2 / day / bar. This is particularly important when packaging a bleach containing oxygen-expanding products, which must be removed as it is expanded in order to prevent the packaging from breaking. The transmissibility of aromas is also an important factor of the film. It is desirable that the aroma of the household product can be detected from the outside of the package. In this regard, the film should be able to transmit about 1 to 25 weight percent of the aroma and preferably about 3 to 15 weight percent of the aroma over a period of 90 days. However, since the aroma is contained in the product to enhance the product during use, much of the aroma must remain in the product and must not be transmitted through the film.

In addition, in order to perform a good RF seal, the film should have a life span from manufacture of about 2 to 24 weeks and, preferably, about 4 to 20 weeks. This lifetime will make the RF seal of the film obtained maximum. It was found that the films have a period, after manufacture, during which maximum resistance is obtained in RF seals. In this regard, bags and other containers must be formed during this period.

time interval in which the film can be sealed more readily will depend greatly on the amount of sliding agent that has been added to the film. The amount of sliding agent contained in the films in question will reach between 500 to 3000 parts per million (ppm) of film resin. Usually, the gliding agent is a wax and, preferably, an amide wax. The rolling tension of the film (film tension on the coil) will also affect the migration of the sliding agent to the outside of the film. It is the migration of the sliding agent to the outer surfaces of the film that causes poor RF seals. When a film is wound at high tension in a reel, less migration of the sliding agent to the surface of the film occurs. The said agent is mostly contained in the film. However, it is free to migrate when the film is unwound for various operations, such as printing and cutting.

The RF sealing of a film will have to be carried out in a time interval that depends mainly on the sliding agent content of the film, the duration of the initial winding tension (Tl), and the time after unwinding to conduct one or more operations, such as printing and cutting (T2). Due to the stability of the film with the initial winding tension, the time (T1) will be reasonably long. The time (T2) will be less than (Tl) since there is a greater migration of sliding agent from the film during (T2). The time interval for use, (T1 + T2), will be about 2 to 24 weeks, with (T2) being at least about 2a about 6 weeks. The time interval for any particular film can be defined only by testing the film over a period of time.

The RF fence is normally conducted at frequency levels of about 10 megahertz (MHz) to 50 MHz, but preferably 13.56 MHz, 27.12 MHz or 40.68 MHz. Of these frequencies, the preferred one is 27.12 MHz. Enough energy is used to soften the ethylene-vinyl acetate layers quickly, so that these layers can be quickly welded to form a sealed bond.

The film package can be performed and then filled or it can be formed and filled in a continuous operation. These latter techniques are known as forming / filling techniques.

The bleach is an aqueous solution of sodium hypochlorite. It is sold in diluted solutions of about 5 to 12 weight percent sodium hypochlorite. What remains is mostly water but may include additives, such as preservatives, surfactants and perfumes. The film pockets in which the bleach is packaged range from 100 cc packaging. to 500 cc packages. A useful size is 250 cc. It is also preferable that the film packages have a bio at the upper end, with the mouth shaped as a nozzle. Such a nozzle facilitates consumer use of the bleach or other household product that is contained in the packaging. Figure 1 shows a suitable packaging of this type. In this set, a film package (10) with a longitudinal RF seal (12) on the rear side is shown. The lower edge has an RF seal (13) and the upper edge has an RF seal (14). This film package has a spout (15) that has been formed in the package. The seal (16) seals the pouch in the nozzle area. This beak is similar to a mouth. This is the preferred packaging. These concepts can be part of another package.

previously mentioned discloses a preferred set of the present invention. Modifications and variations can be made to achieve particular objectives. However, such modifications and variations will form part of the present invention.

Claims (7)

13. - Material sheet for the production of bags intended to contain substances, which consists of a series of layers of film in which at least one layer of the film is a barrier layer and at least one layer of film is a sealing layer , said series of film layers having at least partial transmissibility for aromatic substances, an oxygen transmissibility of at least about 600 cm3 / m2 / day / bar, said series of film layers having a life time of about from 2 weeks to 24 weeks. 23. A sheet of material for producing bags according to claim 1, wherein said barrier layer is a polyolefin and said seal layer is an ethylene-vinyl acetate. 33. A sheet of material for producing bags according to claim 2, wherein said ethylene vinyl acetate layer has an average vinyl acetate content of at least about 18 weight percent. 43. A sheet of material for producing bags according to claim 1, wherein said barrier layer has a thickness of about 25 to 100 microns and said sealing layers have a thickness of about 50 to 200 microns. 53. A sheet of material for producing bags according to claim 1, wherein the series of film layers have a life span of about 4 weeks to 20 weeks. 6th. A sheet of material for the production of bags according to claim 1, wherein the series of layers of film have a life span that depends on the content of the film's slip promoting agent. 7th. - Pouch containing a substance, consisting of a sheet of material sealed to form a closed volume and having a series of layers of film, at least one layer being a barrier layer and at least one layer being a sealing layer , said series of layers of film having at least a partial transmissibility for aromatic substances, a transmissibility for oxygen of at least about 600 cm3 / m2 / day / bar, said sheet of material having a life time of about 2 weeks to 24 weeks before being turned into a purse. 8th. The pouch according to claim 7, wherein said barrier layer is a polyene and said seal layer is an ethylene-vinyl acetate. 9a. The pouch according to claim 8, wherein said ethylene vinyl acetate layer has an average vinyl acetate content of at least about 18 weight percent. 10th. The pouch according to claim 7, wherein said barrier layer has a thickness of about 25 to 100 microns and said seal layer has a thickness of about 50 to 200 microns. llâ. A pouch according to claim 7, wherein said sheet of material has a life span of about 4 weeks to 20 weeks. 12th. A pouch according to claim 7, wherein said series of film layers has a life time which depends on the content of the film's slip promoting agent. 133. The pouch according to claim 7, wherein the upper area has a spout. 143. - Scholarship formation method characterized by: (a) a multi-layered film is formed having at least one barrier layer and a sealing layer, said multi-layered film having an oxygen transmissibility of at least about 600 cm3 / m2 / day / bar and at least partial transmissibility for flavorings; and (b) within about 2 to 24 weeks after the formation of said film, converting it into a bag, by sealing the overlapping edges of said bag using RF energy. 153. The method of claim 14 wherein said barrier layer is a polyolefin and said seal layer is ethylene vinyl acetate. 163. The method of claim 14 wherein said ethylene vinyl acetate layer has an average vinyl acetate content of at least about 18 weight percent. 173. The method of claim 14 wherein said barrier layer has a thickness of about 25 to 100 microns and said sealing layer has a thickness of about 50 to 200 microns. 18th. Method according to claim 14, characterized in that the multi-layered film has a life span of about 4 weeks to 20 weeks. 19. A method according to claim 14 characterized in that said multi-layered film has a life time that depends on the sliding promoting content of the film. 20â. Method according to claim 12, characterized in that a nozzle is formed in a part of said bag.